This invention relates to an engine fuel injection system and control method and more particularly to an improved, simplified, highly effective and yet low cost arrangement for such a system and control.
In internal combustion engines, a wide variety of systems and methodology are employed for engine fuel injection control. Generally, smaller and lower volume engine applications incorporate generally less sophisticated controls than those employed on larger production volume engines such as automotive engines. Even in the small displacement lower production volume engines, for example those used in motorcycles, the engine fuel injection control can become quite complicated.
For example and as shown in FIG. 1, the fuel injection control for a motorcycle engine is shown schematically. The control arrangement is intended to control the timing and duration of fuel injection from a fuel injector 21 associated with an internal combustion engine 22 that powers the motorcycle, which is not shown in this figure, but which may be of a construction as generally shown in FIG. 2. A control signal xe2x80x9cixe2x80x9d is applied to the fuel injector 21 that is supplied with fuel from a fuel supply system, indicated generally at 23 by a fuel injection control circuit arrangement, indicated schematically at 24. This fuel injection control circuit arrangement 24 receives the inputs from a number of engine-associated sensors.
These sensors include a crankcase rotational speed sensor 25 which may comprise a pulser coil and a throttle position sensor 26, which is coupled to the throttle control mechanism for the engine 22 for controlling the position of a throttle valve 27 and inputs a signal to the control 24 indicative of engine load and/or operator demand.
Electrical power is provided to the injection control circuit arrangement 24 from a battery 28 through a main switch 29. This battery power is applied to a power source circuit 30 of the fuel injection control circuit arrangement 24 and specifically to an electronic circuit 31 which may comprise a microprocessor.
The output from the engine speed sensor 25 is transmitted to a rotational speed detector circuit 32, which counts the number of pulses generated in a time period so as to determine the rotational speed of the crankshaft of the engine 22.
This outputs a speed signal N to a fuel injection timing and duration (amount) control determining circuit, indicated at 33. In addition, the throttle position sensor 26 inputs a signal to a throttle position detector circuit 34. This detector circuit 34 outputs a signal A to a throttle opening calculating circuit 35. This, in turn, outputs a throttle angle position xcex8 to the fuel injection timing and duration (amount) control circuit 33.
From these inputs, the fuel injection timing and duration (amount) control circuit 33 outputs a signal at times determined from maps contained in a memory of the circuit 31 to an fuel injection timing and duration (amount) control circuit 36 to output a timed electrical output xe2x80x9cixe2x80x9d of predetermined length to the fuel injector 21 for operating it in a well-known manner.
Various maps may be incorporated in the circuit 31 and to determine how long and when the fuel injection is varied in response to engine speed for given load as determined by the throttle opening circuit. There may be a family of such curves so as to vary the injection timing and duration in response to both throttle position and engine speed.
The introduced charge is then ignited by a spark plug 37 that is fired in any desired manner including that described in the aforenoted copending application, Ser. No. 09/682457.
Rather than using a throttle position sensor, load may be sensed by intake manifold vacuum. Either method, however, requires added sensors, transducers and circuitry.
It has been found that merely using engine speed and load as detected by something such as a throttle position or intake manifold vacuum sensor does not actually provide as good a control as desired. That is, these two factors by themselves may not be sufficient to provide the desired degree of control.
Although systems have been provided for automotive applications wherein more sophisticated controls are employed, this further adds to the cost of the system and does not always provide the optimum results.
There have also been other devices than throttle position sensors or vacuum sensors for sensing intake manifold vacuum for determining engine load. It also has been determined that engine load may be found by comparing engine speed from one revolution to another. However, these systems also tend to be complicated and do not lend themselves particularly low production volume, low cost vehicle applications. They also have the disadvantage of requiring a plurality of different types of sensors.
Other arrangements have been proposed wherein engine speed is measured for less than one complete revolution of the engine and variations from cycle to cycle have been employed to determine engine load. These systems, however, have for the most part, required multiple sensors and also require some delay from the sensed conditions before adjustment is being made.
It is, therefore, a principal object to this invention to provide an improved engine control system wherein the number of sensors employed for achieving optimum engine fuel injection control is substantially reduced.
It is a further object to this invention to provide an arrangement for controlling an engine fuel injection system utilizing only a single sensor and a single timing mark associated with a driven engine shaft so as to substantially reduce the costs, without significantly decreasing the efficiency or the obtaining of an optimum control.
A first feature of this invention is adapted to be embodied in an internal combustion engine fuel injection control system. The engine has a driven shaft and a sensor arrangement is associated with the driven shaft for sensing the instantaneous rotational speed of the driven shaft during the rotation of the driven shaft for less than a complete rotation and for sensing the rotational speed of the driven shaft for a complete revolution that includes the measured less than complete rotation. In accordance with the apparatus, the engine fuel injection system is controlled from these measurements.
Another feature of the invention is adapted to be embodied in a four-cycle internal combustion engine fuel injection control. In accordance with the apparatus, the engine has a driven shaft and a sensor arrangement is associated with the driven shaft for sensing the rotational speed of the driven shaft. The rotational speed of the driven shaft during a revolution containing a compression stroke and during a revolution containing an exhaust stroke is made. The engine fuel injection is controlled from these measurements.
Another feature of the invention is adapted to be embodied in a fuel injections system for an internal combustion engine. The engine has a driven shaft and sensor is associated with the driven shaft for sensing two rotational conditions of the driven shaft during a first rotation thereof. The same two rotational conditions are sensed during the immediately succeeding rotation of the driven shaft and the engine fuel injection system is controlled on the third rotation of the driven shaft from these measurements.